Among the many problems associated with the utilization of nuclear fission is the disposal of radioactive waste materials. In the day-to-day operation of nuclear power plants there are aqueous evaporator wastes that are not only radioactive but range from highly acidic to highly alkaline and of diverse solute composition.
Also ion exchange resin beds are utilized to deionize the water used in the plant. Those beds require replacement from time to time. The heat exchanger bundles and other elements of the plant require descaling and other cleaning from time to time resulting in significant quantities of radioactive waste cleaning solutions.
One technique for disposal of such radioactive liquid wastes is to encapsulate the waste in a solid and to bury that solid in a designated place. In the past both concrete and urea-formaldehyde resins have been employed as the encapsulating material. Cement does not cure properly under acidic conditions, so that the acidity must be neutralized before encapsulation or a different material must be used. Also concrete is very heavy, handling is cumbersome and transport to the remote burial site is expensive.
Urea-formaldehyde resins have also been employed as the encapsulating material. However, because of a requirement of acidic cure and because of shrinkage during cure much of the aqueous material bleeds out of the solid. Also such resins result in undesirably high leaching rates in the fully cured state.
Nuclear plants also have problems with the disposal of radioactive finely divided solids. Those solids may be radioactive themselves or they may be absorbed on finely divided materials, such as filtering aids including, for example, various clays and charcoal.
Waste materials other than radioactive substances also present a waste disposal problem. For example, the heavy metal wastes from electroplating operations are very difficult to dispose of in an environmentally safe manner.
Another vexatious disposal problem involves the disposal of the toxic wastes from insecticide plants.
Many other disposal problems are a challenge to the ecological conscience.